The Burning Question

How does a runner stay on the slim side of the calories consumed equation? Here are five easy answers

Despite what many inventors of best-selling fad diets would have the public believe, weight loss is a simple issue. Burn more calories than you consume, and you'll lose weight. As a runner, you're in luck, because running happens to be one of the best and fastest ways to expend energy. To lose one pound, you need to burn 3,500 more calories than you eat. And running burns about 100 calories per mile. Running also keeps your metabolism elevated for hours after your workout, meaning you burn more calories even while you're sitting at your desk at work or on the living room couch recovering from your run.

But hold on before you reach for that extra jelly doughnut. Runners face a frustrating truth: Research has shown that the postworkout metabolic rate is elevated longer in untrained subjects. As you become more and more fit, you recover faster, so your postworkout metabolic rate returns to its resting level sooner, and you don't burn as many calories as your neighbor who runs only occasionally.

You're just going to have to make up for it during your workout, when your metabolic rate is at its highest anyway-and therefore has a greater impact on your calorie burn and subsequent weight loss. Here are five simple ways to shake up your training to blast more calories. All of these modifications are worth the extra effort: You'll achieve the dream of almost every runner-to get slimmer and faster.

Log More Miles

Adding more miles to your week is probably the easiest and most obvious way to burn more calories. By running five to 10 more miles per week, you'll burn an extra 500 to 1,000 weekly calories. And it's more exciting than it sounds: The farther you run, the better your body gets at conserving carbohydrates and relying on fat as fuel. You become a better fat-burning machine.

A good way to start burning more calories is to add one mile (or five to 10 minutes) to each of your daily runs for three weeks; then back off for a recovery week. After your recovery week, continue to add miles (or time) in the same fashion.

Go Long

A weekly long run burns more calories two ways. First, there's the 100-calorie-per-mile expenditure: run 15 miles and you burn an impressive 1,500 calories. You may even burn more than 110 calories per mile, depending on the amount of oxygen you use while running and your body weight. (It costs more oxygen to transport a heavier person.) Women, alas, burn fewer calories per mile than men, since they typically weigh less.

Long runs not only burn more calories; a number of studies show that they also help boost your postrun metabolic rate, often exponentially. A study published in Medicine & Science in Sports & Exercise found that the longer that subjects walked at 70 percent of maximal oxygen consumption, or VO2 max, the longer it took for their metabolic rates to return to pre-exercise levels. In another study, published in Canadian Journal of Sport Sciences, postworkout metabolic rates more than doubled when the amount of time subjects exercised increased from 30 to 45 minutes-and increased more than five-fold after exercising for 60 minutes.

To reap the weight-loss rewards of going long, start your weekly long runs about two minutes per mile slower than your 5-K race pace. Increase their length by five to 10 minutes (or one mile) each week for three or four weeks before backing off for a recovery week. If you run more than 40 miles per week, or if you run faster than an eight-minute mile, you can add two miles at a time to your long run. Your long run should make up no more than 30 percent of your weekly mileage.Pick Up the Pace

Of course, you'll reach a point-physically, psychologically, professionally-where you can't add more weekly mileage or miles to your long run. That's when you'll have to pick up the pace, and running at your lactate threshold is an excellent way to do that. Your lactate threshold marks the point between almost exclusively aerobic running and efforts that include significant anaerobic (oxygen-independent) metabolism. It tells you the speed at which you cross into a domain that makes running more difficult and fatigue imminent. Stay right on that edge, and you're at an ideal pace for torching calories: You're working at the highest sustainable rate of aerobic energy expenditure.

The lactate threshold also represents the transition between your reliance on a combination of carbohydrates and fats versus carbohydrates as a sole source. The two fuels provide energy on a sliding scale-as you increase your pace to your lactate threshold, your need for fat decreases while your reliance on carbohydrates increases. Many people who have heard some version of this are inclined always to exercise at lower intensities to burn more fat. Yet research shows that exercising at or slightly below your lactate threshold intensity elicits the highest rate of fat oxidation. Although the percentage of calories from fat is indeed small when running below your lactate threshold pace, the total number of calories expended per minute is much higher than at a lower intensity.

From a performance standpoint, lactate threshold runs give you the best aerobic bang for your buck, raising your threshold to a faster pace. Increasing the speed at which your threshold occurs allows you to run faster before you fatigue. The benefit to being able to run aerobically at an eight-minute pace compared to an 8:30 pace is obvious.

To burn more calories and up performance, introduce one of the following lactate threshold workouts each week. The pace, which should feel comfortably hard, is about 10 to 15 seconds per mile slower than 5-K race pace (or about 10-K race pace) for slower, recreational runners; for those more highly trained, it's about 25 to 30 seconds per mile slower than 5-K race pace (or about 15 to 20 seconds per mile slower than 10-K race pace).

3 to 4 x 1 mile at lactate threshold pace with one minute rest

15 to 20 minutes at lactate threshold pace

Now Pick It Up a Bit More

While the pace you run does not affect how many calories you burn during a run of a specific distance, it does affect how many calories you burn afterward. A number of studies have shown that the more intense the exercise, the more and longer your postworkout metabolic rate is elevated-and the more weight you subsequently stand to lose. In a study published in Medicine & Science in Sports & Exercise, triathletes who cycled at 75 percent VO2 max for 20 minutes burned more calories after their workout than they did after cycling at just 50 percent VO2 max for 30 or 60 minutes.

Another study published in Journal of the American College of Nutrition compared metabolic rates following two equal calorie-burning workouts: a short-duration, high-intensity workout (51 minutes at 75 percent VO2 max) and a long-duration, low-intensity workout (78 minutes at 50 percent VO2 max). The researchers found that the high-intensity workout left the subjects with a higher postworkout metabolic rate than the low-intensity workout did.

To add some intensity and make your metabolism work for you long after your workout, try one of the following interval runs each week. Recreational runners should limit high-intensity workouts to once a week. If you're a veteran, you can try adding two into your weekly training program:

Although it takes more time out of your day to run twice, it's easier to run a four-miler in the morning and a six-miler in the evening than it is to run one eight-miler. Physically, the two smaller sessions give your body a break; psychologically, you only have to get your head around the shorter distances. So you're increasing your mileage-and calories burned-while taxing your body and mind less.

Splitting your run into two shorter runs will also result in two separate elevations in your postworkout metabolic rate-which will give you two opportunities to burn more calories during the day. One study, published in British Journal of Sports Medicine, had women run for 50 minutes at 70 percent VO2 max one day and twice for 25 minutes at the same intensity another day. The combined increase in postworkout metabolic rate was higher after the two workouts than after the single workout. By running twice per day, you double the afterburn effect. And you're going to stay on the right side of the calorie-burning equation.